<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- <link rel="stylesheet" href="/style/holy"> -->
</head>
<body>
    <main>
        <div class="center">center</div>
        <div class="left">left</div>
        <div class="right">right</div>
    </main>

    
</body>
<style>
    *{
        box-sizing: border-box;
        /* margin: 0; */
        /* padding: 0; */
    }
    main{
        padding: 0 100px;
        width: 100%;
        
    }
    main::after{
        content: '';
        display: block;
        clear: both;
    }
    div{
        height: 200px;
        float:left;
    }
    .center{
        
        width: 100%;
        background-color: aliceblue;
    }
    .left,.right{
        background-color: aqua;
        width: 100px;
        position: relative;
    }
    .left{
        margin-left: -100%;
        left: -100px;
        
    }
    .right{
        margin-left: -100px;
        right: -100px;

    }
</style>
</html>